Various wireless systems are becoming popular, including car navigation systems and mobile handsets equipped with GPS (Global Positioning System). With the spread of ETC (Electronic Toll Collection) systems, development of a vehicular antenna that can cope with circularly polarized waves of multiple frequencies from GPS and ETC systems is being sought for car navigation systems. Furthermore, development of compact, circularly polarized antennas that can be housed not just in a car navigation system but also in a small mobile handset casing, such as a cell phone, digital camera, PDA, wristwatch and/or the like, is being sought.
With regard to compact circularly polarized antennas, a patch antenna that uses ceramics with high dielectric constants is widely used.
However, a patch antenna using ceramics with high dielectric constants is heavy, making construction onerous and thinness difficult to achieve.
A compact multi-frequency antenna with large benefits, with which compactness and light weight are possible with multiple frequencies, is disclosed in Non-Patent Literature 1.
However, this antenna is linearly polarized and is not compatible with circularly polarized waves.